This invention concerns sharpening apparatus and more particularly bedknife grinders for sharpening the bedknife used with reel type mowers.
Reel mowers consist of a set of helically formed blades arranged in a generally cylindrical shape. The blades are rotated against a bedknife closely positioned along the perimeter of the reel blade array. Grass being mowed is sheared as each segment of the blades rotate to progressively reduce the clearance with the bedknife, shearing the grass blades between the blades and the bedknife.
Bedknives become dulled with use, such as to require periodic sharpening and truing of the surface defining the clearance space with the blades of the reel blade array.
Bedknives are mounted to the mower op a pair of pivotal mounts fixed to either end of the bedknives. The bedknives clearance is set by a centrally located adjustment attachment, which rotates the bedknife relative to the reel during adjustments, thereby adjusting the cutting clearance.
In conventional sharpening apparatus for bed knives, the bedknife blade has its pivots mounted on a pair of opposing aligned centers, clamped to a rail extending parallel to the ways along which the grinding wheel is traversed during grinding. The bedknife is aligned with the axis of motion of a grinding wheel by means of a fixture gauge with one center being adjustably mounted, such as to enable shifting of the axis of the bedknife relative to the grinder ways in order to render the axis extending through the bedknife centers parallel with the grinder ways.
A separate center support must be installed afterwards to afford sufficient stiffness of the bedknife during grinding.
This manual alignment adjustment is tedious and time consuming, and subject to error. In addition the bedknife often receives a heavy pounding during mowing, such that the pivots on either end often are bent to become substantially out of alignment with each other. Accordingly, the set up procedure described being dependent on the pivots being aligned is ineffective in such instances.
It is the object of the present invention to provide an improved method and apparatus for sharpening bed knives for reel type mowers, which eliminates the need for adjustment of the bedknife supports, which does not depend on the correct alignment of the bedknife pivots and is much less subject to errors in set up.